Trip-free construction on reset controls



Filed Sept. 20, 1967 w. .1. SANDERS 3,497,852

TRIP-FREE CONSTRUCTION ON RESET CONTROLS 2 Sheets-Sheet 1 ,IOO H2 96 IIIERBZ IS? I I H8" Hi8 88 L [04 --IO4 I 88 'I/ I Ill/fl I FIG-4 INVENTOR. WILLIAM J. SANDERS HIS ATTORNEYS Feb. 24, 1970 w. J. SANDERS TRIP-FREE CONSTRUCTION ON RIEISET CONTROLS 2 Sheets-Sheet 2 Filed Sept. 20. 1967 FIG-5 I40 I34 I30 I32 INVENTOR. WILLIAM J. SANDERS HIS ATTORNEYS United States Patent 3,497,852 TRIP-FREE CONSTRUCTION ON RESET CONTROLS William J. Sanders, Greensburg, Pa., assignor to Robertshaw Controls Company, Richmond, Va., a corporation of Delaware Filed Sept. 20, 1967, Ser. No. 669,175

Int. Cl. H01h 71/10 US. Cl. 337-321 Claims ABSTRACT OF THE DISCLOSURE A trip-free construction on reset controls, such as thermostatic controls for cooking appliances and the like. Any

condition responsive control that is provided with a manual reset and the like, is provided with a trip-free construction which prevents a user from setting the reset push button or the like in actuated or pushed in position to cause continuous energization of the controlled apparatus independently of an unsafe condition in the apparatus being controlled. That is, means are provided for preventin-g any usefulness or desirability in locking a reset push button in pushed in condition to prevent the thermostat from stopping a heating operation, under overheated conditions. For example, the second or circuit breaking lever which, according to this invention, is opened when the thermostat responds to an overheated condition is maintained in open position by the pushed in push button, to break the control circuit as long as the push button is in. Such lever can only be closed by releasing the push button to enable the thermostat thereafter to operate in the normal manner.

This invention relates to a trip-free construction on reset controls and the like.

One of the features of this invention includes a controller construction, such as a thermostat, which prevents a reset member from causing the control construction to be operative While the reset member is in actuated or pushed in condition.

Another feature of this invention includes a controller construction in which the safety circuit opening member or lever cannot be returned to closed circuit condition while a reset member is in actuated, or pushed in condition, and such lever and the like can only return to closed position after, or while such reset member is being returned to its released condition.

For example, controllers, such as thermostats and the like are manufactured with a reset member which may be an inwardly pushed button for resetting the thermostat if the same is opened under response to injurious or undesirable controlled conditions. It has been a dangerous practice to lock these reset members or push buttons in actuated or pushed in condition, so that the control will continue to operate the apparatus regardless of undesirable or dangerous conditions. Such push buttons are often held down by adhesive tape or the like, so that the thermostat continues to energize the controlled member even after an undesirable or dangerous condition has been produced in such controlled member.

According to this invention, such thermostat is provided with means for preventing the thermostat from becoming reoperative while the reset member or push button is in actuated or pushed in condition. Such thermostat can only become reoperative after the reset member or push button has been released or allowed to return to normal position. By such construction, it the push button is taped down, the thermostat cannot energize the controlled member, and this previous dangerous practice is prevented.

By way of example, certain thermostats which are marketed by the Robertshaw Controls Company, having a along the line 5-5 of FIGURE 2.

3,497,852 Patented Feb. 24, 1970 place of business at Richmond, Va., may be provided with the features of this invention. A thermostat, designated by said company as Type H-l, may be provided with this invention, and the disclosure will be made in this application in connection with such thermostat Type H-l. However it is to be understood that the invention is applicable to many other or different controls, in view of this disclosure. Among such many other controls, the controls Type H44, and Type H-2, of said Robertshaw Controls Company may also be provided with the features of this invention.

Other features of this invention are apparent from this description, the appended claimed subject matter, and/or the accompanying drawings, in which:

FIGURE 1 is a diagrammatic front view of the thermostat, such as said Type H-l thermostat.

FIGURE 2 is a diagrammatic cross section generally along the line 2-2 of FIGURE 1, with certain parts shown which are to the right of line 2--2.

FIGURE 3 is a diagrammatic cross section taken gen erally along the line 3-3 of FIGURE 2.

FIGURE 4 is a diagrammatic cross section taken generally along the line 4-4 of FIGURE 3.

FIGURE 5 is a diagrammatic view taken generally FIGURE 6 is a side view of the apparatus, with certain parts broken away, taken from the opposite side from that of FIGURE 2, such as from the left side of FIG- URE 1.

FIGURE 7 is a diagrammatic cross section taken along the line 77 of FIGURE 5.

FIGURE 8 is a diagrammatic cross section of certain parts which are shown in FIGURE 2, in the position obtained when the thermostat is being opened, and before it reaches an over temperature condition, the safety lever being shown in full line position during safe condition operation and being shown in dotted line open position, when actuated during undesirable condition of the controlled apparatus to break the circuit.

FIGURE 9 shows the parts of FIGURE 8, with the thermostat responding to cool conditions, but with the safety lever in open position to prevent reenergization of the controlled apparatus.

FIGURE 10 shows the parts of FIGURE 9, with the reset button pushed in or actuated condition and holding the safety lever in open position until after the push button in released.

FIGURE 11 shows the parts of FIGURE 7 when the push button is in actuated or pushed in condition, and the safety lever being held in open position.

Certain words may be used in connection with this specification and claimed subject matter which indicate direction, relative position, and the like. Such Words are used for the sake of brevity and clearness. However, it is to be understood that such words are used only in connection with the views of the drawings and that in actual use, the parts so designated may have entirely different direction, relative position and the like.

The US. patent to Victor Weber, No. 2,389,880, patented Nov. 27, 1945, is referred to herein for the purposes of this disclosure. Such Weber patent discloses a thermostat, without the features of this invention, which is an early embodiment of the thermostat type H-1 above referred to. Certain elements in this application which are similar to corresponding elements in the patent will be designated in this application by similar reference characters to those of the patent, so that the analogy will be more readily understood. The elements designated herein by numerals below 141, correspond, in general, to similar elements designated by similar reference numerals in said patent. Elements designated above 141 in this application are intended to designate parts not specifically designated by reference numerals in the Weber patent. Also the parts added to the Weber patent and which embody features of this invention are designated by reference numerals above 141.

A controller, such as said controller or thermostat Type H1, similar to that disclosed in said Weber patent, may have an L-shaped frame and channelshaped cover 14. A scale 26 shoWs temperatures or conditions of the controlled apparatus 142 to be produced under control of the controller or thermostat. A pointer. 28 indicates the temperature or condition to which the controller or thermostat is adjusted. However, in the actual thermostat Type H-l, a knob is substituted, which is not shown herein.

An adjusting screw 30 is turned by rotation of the pointer 28 and has a projecting end within the cover 14, which end engages an expansible and contractible diaphragm 36. The interior of the diaphragm 36 is connected to a capillary tube 40 and a temperature sensing bulb 42 so that the bulb may be placed in the oven 142 or other device or apparatus to be controlled, to expand and contract the diaphragm 36 in response to the conditions or temperatures in the apparatus or oven. A button or rod 44 extends from the face of the diaphragm 36 and abuts a. depression 46 in a main actuating lever 48. This lever '48 has an upper knife edge 50 which is fulcrumed on a pair of knife-edged bearings 52 on a pair of brackets 54 which are secured to the L-shaped frame 10.

The lower end of the actuating lever 48 has an opening 55 for one end of a tension spring 56. The other end of the spring 56 is hooked in an aperture in the center cross bar 58 of an R-shaped control lever 60.

The two legs 62 and 64 of the control lever have knife edges 63 to cooperate with knife-edged bearings 65 in support brackets 66 which are carried by the frame 10.

The control lever 60 is connected by suitable means described in the patent to reciprocate horizontally an insulating contact block 86 which carries a pair of contact bridges 88 which are secured in each end of the contact block 86 for cooperation with stationary contacts 90, 92, 94 and 96 Which are mounted on the insulating block 16 at the top of the thermostat.

Contacts 90, 92 and 96 are provided with terminal connectors also designated as 90, 92 and 96 such connectors having wire holding screws 98. However, the contact 94 is adapted for permanent connection with a conductor 100, FIGURE 4, which is connected to a stationary contact 104, to be further described.

It will be apparent from the foregoing description, as well as the more detailed description in the patent, that the contact block 86, and the contact bridges 88 are reciprocated with snap action in response to the temperature in the oven, which causes contraction and expansion of the diaphragm 36, gradual rocking of the actuating lever 48, and snap acting reciprocation of the control lever 60 by the snap spring 56, as the lower end of the actuating lever 48 passes back and forth past the fulcrum point 65 of the lever 60.

Additional stationary contacts 102 and 104 are carried by the insulating block 16 behind the contacts 94 and 96. The lower ends of contacts 102 and 104 have contacts to be engaged by the contact bridge mounted on an insulating plate 112 which is carried by the upper end of flexible metal member 114 of a secondary lever 116.

Contacts 90 and 96 may be connected to the line wires 106 and 108, while the contacts 92 and 102 are connected to the heating element 109 in the oven 142.

The levers 60 and 112 comprise first and second parts of a movable means of the switch construction that is operated by the temperature responsive means 36 through two ranges of movement thereof in a manner hereinafter described.

The secondary lever 116 is reciprocated out of contact with the contacts 102 and 104, when the thermostat actuating lever 48 overshoots in response to an undesirable condition or too high temperature in the oven, or the like. Thus, when the secondary lever 116 is opened and disconnects the contacts 102 and 104, the circuit to the heating member 109 is broken, to prevent further heating of the oven until lever 116 returns into contact with contacts 102 and 104. The lever 116 will be locked automatically in open position, so that it cannot return into contact with the contacts 102 and 104 until the lever 116 is reset by actuation, or pushing in of the reset button 138 in a manner to be described.

In thermostats not having the features of this invention, yet to be described, a user can lock or tape the reset button 138 in actuated or pushed in position, and then the thermostat can energize and deenergize the heater 109. However, if the heater should overheat the oven, such taped thermostat cannot lock lever 116 in open position to prevent dangerous operation of the heater 109. According to features of this invention, it the push button 130 is maintained in actuated position the thermostat cannot energize the heater.

The secondary lever 116 is fulcrumed on arms 73 which are carried by the frame 10.

The lever 116 has lateral projections 118 which extend into openings in the arms 73, so that the lever 116 pivots about the projections 118 on arms 73.

The lever 116 is spring biased away from the contacts 102 and 104 by a holding spring means or spring 120 which is shown in the patent as a coil spring 120 and is illustrated therein as a leaf spring 120. The lever 116 is biased clockwise in FIGURES 2, 8, 9 and 10, and counterclockwise in FIGURE 6 by the spring 120.

The secondary lever 116 is located in such position that it is beyond the normal range of movement of the over center snap action of the main actuating lever 48. The normal movement of the actuating lever 48 can occur without directly aifecting the position of the secondary lever 116 in either contact engaged or disengaged position. In order to provide for operation of the contacts 102, 104 and 110 by excessive or abnormal movement of the main actuating lever 48 beyond the normal or safe range of the over center snap action, interengaging means are provided to release the lever 116 to open position and to lock said lever 116 in open position until reset by the reset button 138.

Such interengaging means may include the rocker 122 which has a notch 136. The rocker '122 is rocked counterclockwise in FIGURES 2, 8, 9 and 10 when the actuating lever 48 overshoots in response to an excessive temperature in the oven 142. This rocking movement releases the lever 116 from the position of FIG- URES 2, 8 and 10 to the dotted position of FIGURE 8 and the position of FIGURE 9. The push button 138 rocks the lever 116 counterclockwise from the open positions of FIGURES 9 and 10 to the full line position of FIGURE 8 when the push button is pushed in, then released.

The rocker 122 pivots on pivot 123 and has a wedging ramp 126 which is engaged by a lateral projection 128 of actuating lever 48.

When ramp 126 is engaged by the lateral projection 128 of lever 48 the projection rides along the ramp 126 and pushes it down to tilt the rocker 122 during the further movement of the lever 48- beyond the usual range. The rocker 122 is pushed upwardly by the U-shaped spring metal spring strip 130.

The opposite end of the rocker 122 is urged by spring 130 about the pivot 123 toward a projection 132 which is formed on a depressed portion 134 of the secondary lever 116.

Latching engagement between the secondary lever 116 and the rocker 122 is secured by forming the end of the rocker 122 adjacent the projection 132 with a notch 136 with which the projection 132 may engage. The projection 132 and notch 136 provide locking and releasing actions for the lever 116 as illustrated in the various FIGURES 8, 9 and 10.

The secondary lever 116 is in unlatched position in FIGURE 9 after the rocker 122 has been engaged and pushed down by the lateral projection 128 of lever 48.

In the position of FIGURE 9 the spring 120 (shown in FIGURES 6 and 8) has biased the lever 116 from normal latched position to the unlatched position so that the bridge 110 is separated from the contacts 102 and 104 to break the circuit to the heater 109. The lever 116 will remain in the position of FIGURE 9 until the push button 138 is pushed in to cause the pin 140 to push the lower end of the lever 1-16 at the extension 150, FIGURE 3, which causes the lower end of the lever 116 to move rightward in FIGURES 9, 10 and 8 far enough so that the right end of the rocker 122 can move past the lateral projection 132 and move to the latched position shown in FIGURES 10 and 8. The pin 140 is normally biased leftward in FIGURES 9, 10 and 11 by a compression spring 143, so that it normally returns to unactuated position of FIGURES 8 and 9 from the actuated or pushed in position of FIGURE 10.

The operation of the switch described so far is described fully in the said Weber patent, and has been partially described herein and illustrated, in order to now more fully disclose the subject of this invention.

It should be noted that in the patent controller not having the features of this invention, the flexible portion 114 of lever 116 connot be held in the flexed open position of FIGURE 10. Instead the patent level 116 and its flexible portion 114 are immediately pushed to closed URE 10 and then tape the push button in that position of FIGURE 10, so that the push button could be taped in the FIGURE 10 position to maintain the lever 116 continuously closed.

THE TRIP-F REE CONSTRUCTION The trip-free construction of this invention will now be described.

The construction is such that the user cannot push the push button 138 inwardly to the position shown in FIG- URE 10 and then tape the push button in that position for the purpose of having the thermostat operate continuously regardless of any overshoot in the temperature.

According to this invention, means are provided for holding the flexible portion 114 of the switch lever 116 flexed away from the contacts 102 and 104 as long as the push button 138 is in pushed in position, or rightward position, as shown in FIGURE 10. FIGURE 10 shows flexible portion 114 of the lever 116 flexed right- Wardly by a safety lever means or lever 151, so that the bridge 110 cannot contact the contacts 104 and 102 as long as the reset button 138 is in pushed in position, as shown in FIGURE 10.-

A lever 152 is placed in front of the downward extension 150 of lever 116 so that the pin 140 cannot be pushed in without first engaging the lower end of the lever 152 to rock such lever 152 about its pivot brackets 153. The upper end of the lever 1 52 engages the end 154 of the lever 151 and causes such lever 151 to pivot about its fulcrum point 155 which is provided in one of the brackets 54 which have been previously described.

The left end of lever 151 is pushed toward the viewer in FIGURE by a leaf spring 156, which is secured to the frame 10, and extends upwardly in FIGURE 5 to engage and hook the back of the lever 151.

When the push button pin 140 engages and pushes the lower end of the lever 152, FIGURES 5 and 7, the lower end of lever 152 is first pushed toward the frame 10, and thereafter the downward extension 150 of lever 116 is also pushed toward the frame 10, causing the lower rigid portion 116 of the lever 116 to move forwardly to the position of FIGURE 10. However, the right end (FIGURE 5) of lever 151 engages the flexible part 114 of the lever 116 and holds it back in FIGURE 5 and rightwardly, in FIGURE 10, so that the bridge cannot engage the contacts 102 and 104, as long as the push button 138 and pin are in the rightward position of FIGURE 10. Therefore, if the push button 138 should be taped in its inward position of FIGURE 10, then the circuit would be continuously broken between contacts 102 and 104, so that the heater 109 cannot be energized as long as the push button 138 remains in pushed in position.

However, when the push button 138 is released, without taping, and in the proper manner, then the levers 152 and 151 yield, and allow the flexible part 114 of the lever 116 to move leftwardly in FIGURE 10 to its normal closed postion in contact with contacts 102 and 104 corresponding to the full line position shown in FIGURE 8.

It is to be seen that the actuating lever 48, and the control lever 60 can operate and respond to the expansion and contraction of the diaphragm 36 without any interference by the levers 151 and 152. These levers only hold the flexible part 114 of the lever 116 away from the contacts 102 and 104, as shown in FIGURE 10, when the push button is pushed in, while the levers 48 and 60 can continue to be operated by the diaphragm 36 without interference. However the heater 109 cannot be energized by the levers 48 and 60 as long as the push button is pushed in and held in pushed in condition.

Thus an energy controller construction is provided for controlling the flow of energy, such as electric current, to an apparatus or oven 142 to be controlled by said controller 160, in response to conditions produced in said apparatus by said energy. The controller 160 has energy flow control means, such as the switch means 90, '92, 94, 96, 102 and 104, levers 48, 60, diaphragm 36, etc., in controller 160 to control the flow of said energy in response to desirable and undesirable conditions in said apparatus or oven 142.

Desirable conditions may be temperatures and the like, such as the desirable temperatures ordinarily desired in such oven. Undesirable conditions may be undesirable temperatures and the like such as too hot or dangerous temperatures of said oven. However, the designation desirable conditions is used in a broad sense to designate any usual condition in a controlled apparatus to 'be expected, while the designation undesirable conditions is used in a broad sense to designate any abnormal or alternate conditions that may occur and which is to cause the controller to stop the flow of energy or stop operation of the apparatus. Refrigerators may be provided with features of this invention in which the undesirable condition may be a too low temperature in the food compartment or too hot a temperature in the condensing unit and the like. Other apparatus may be also controlled by controllers other than thermostats and the like. 7 The energy flow control meansor switch means 90, 92, etc., has undesirable condition responsive means, such as the overshoot of lever 48 with rocker 122 to render said energy flow control means 160 inoperative in response to an undesirable (overheated) condition produced in said apparatus or oven 142.

The controller 160 has reset means (138, 140) movable to an actuated condition or position, such as the pushed in condition of button 138, FIGURE 10, and a released condition or position, such as the released condition subsequent to the release of button 138 in FIG- URE 10.

The improvement of this invention may include a first safety means, such as the rigid lever 151 which is provided to prevent the undesirable condition responsive means from restoring the energy flow (electrical flow) control means to reoperative condition (by holding the contact 110 away from the contacts 102, 104 as in FIG- URE 10) while the reset means is in actuated condition 7 (such as the pushed in condition of button 138 in FIG- URE A second safety means (such as the flexible part 114 of secondary lever 116) is provided to restore said energy flow control means 160 to reoperative condition while said reset means (or button 138) is in released condition. This occurs when the button 138, FIGURE 10, is released, which causes the rigid lever 151, FIGURE 10, to move leftwardly away from flexible part 114 so that spring or flexible lever part 114 can also move the upper part of the lever 116 and the contacts 110 leftwardly and close the contacts 110 on the contacts 102 and 104 so that the controller can again control the temperature of the oven 142 by reciprocation of the thermostatically reciprocated contacts 88 into and out of contact with the stationary contacts 90, 92, 94 and 96.

The energy fiow control means of the controller 160 includes a first energy flow device or first switch means 88, 90, 92, 94, 96, having an energy flow condition (switch make) and an energy stop condition (switch break) for controlling the flow of energy to the apparatus or oven 142. It also includes an actuating lever 48 movable back and forth within a normal range in response to desirable conditions in said apparatus to move said energy flow device (first switch means) intermittently to energy flow and stop conditions (switch make and break conditions). Said actuating lever 48 is also movable to an undesirable position (overshoot or undershoot) outside said normal range in response to an undesirable condition in said apparatus or oven.

The undesirable condition responsive means of the controller also includes a second energy flow device or second switch means 102, 104, and 110 having an energy flow condition and an energy stop condition (or switch make and break condition) for controlling the flow of energy to said apparatus or oven 142. Such undesirable condition responsive means also includes the secondary lever 116 movable to energy flow and stop positions respectively moving said second energy flow device, or switch 102, 104, 110, to energy flow (switch make) and energy stop (switch break) position. Such actuating lever 48 moves said secondary lever 116 to its stop position (switch break dotted position, FIGURE 8) when said actuating lever 48 moves to its said undesirable position (overshoot or undershoot just beyond its position in FIGURE 8). The reset means 138 can return the secondary lever 116 to its said energy flow position or switch make position (full line position of FIG- URE 8).

Such secondary lever 116 is normally biased, by spring 120 to its energy stop (switch break position) and has latch means 136 to lock said secondary lever in its energy flow position (switch 'make position) of FIGURE 8 by operation of the reset means or button 138. The latch means 136 is tripped to move said secondary lever 116 to its energy stop position (switch break position) by movement of the actuating lever 48 to its undesirable position (overshoot or undershoot position), such as would occur by overshoot of actuating lever 48 in FIGURE 8 to move rocker 122 and release lever 116 to dotted line position.

The rigid lever means 151 of this invention maintains the secondary lever 116 in its energy stop position (switch 110 break position, FIGURE 10) while the reset means 138 is in its actuated position of FIGURE 10. Said secondary lever 116 is released to move to its energy flow position (switch 110 closed position) while said reset means 138 is in released condition and releases the rigid levers 151 and 152 to permit the lever 110 to flex at flexible part 114 to move the upper part of lever 110 to energy fiow or switch 110 closed position.

Hence, according to this invention, it is not possible to lock or tape the push button in the position of FIG- URE l0, and expect the controller again to heat the oven. It is necessary to release the push button to unactuated position to restore the controller to operative condition. The dangerous practice of locking or taping the push button is therefore eliminated.

It is thus to be seen that an effective means has been provided for preventing the unsafe practice of taping or otherwise holding a push button or other reset button or reset means in an undesirable or unsafe manner.

While the form of the invention now preferred has been disclosed, as required by statute, other forms may be used, all coming within the scope of the invention and claimed subject matter.

What is claimed is:

1. An electrical thermostat for controlling the flow of electrical current from an electrical power suorce to an electrical heating means of an apparatus comprising a housing means, electrical switch means carried by said housing means and having movable means for interconnecting and disconnecting said source to and from said heating means, said movable means having first and sec ond movable parts, temperature sensing means operatively associated with said movable means of said switch means to move the same in response to the temperature effect of said heating means, said first part of said movable means of said switch means having a first range of move ment from its closed position to an open position thereof caused by said temperature responsive means sensing normal temperature effects of said heating means above a predetermined temperature effect thereof, said first and second parts of said movable means having a second range of movement thereof in an opening direction caused by said temperature responsive means sensing abnormal temperature effects of said heating means above said predetermined temperature eifect thereof, holding spring means carried by said housing means for holding said second part of said movable means in said second range thereof when said movable means is moved into said second range of movement thereof, reset means carried by said housing means and being movable relative there to between a released condition thereof and an actuated condition thereof, said reset means being operatively associated with said holding means to overcome said holding means when said reset means is moved to its actuated condition so that said second part of said movable means tends to move from said second range thereof into said first range thereof, and safety lever means carried by said housing means and being operatively associated with said reset means to prevent such movement of said second part of said movable means from said second range thereof to said first range thereof by being engaged against said second part of said movable means by said reset means until said reset means returns to said released condition thereof.

2. An electrical thermostat as set forth in claim 1 wherein said first and second parts of said movable means of said switch means respectively comprise a first switch portion and a second switch portion disposed in series between said power source and said heating means, said temperature responsive means only moving said first switch portion to an open condition thereof when sensing said normal temperature effects above said predetermined temperature effect of said heating means.

3. An electrical thermostat as set forth in claim 2 wherein said temperature responsive means moves both of said switch portions to open conditions thereof when sensing said abnormal temperature effects above said predetermined temperature effect of said heating means.

4. An electrical thermostat as set forth in claim 3 wherein said holding means holds only said second switch portion in its said open condition when said second switch portion moves from its closed condition to its said open position.

5. An electrical thermostat as set forth in claim 4 wherein said first switch portion is operatively associated with said second switch portion to move said switch portion to its open condition when said temperature responsive means moves said first switch portion into said second range of movement thereof.

6. An electrical thermostat as set forth in claim 5 wherein said second switch portion comprises a switch lever means normally biased to its circuit open position, latch means carried by said housing means to lock said switch lever means in its circuit closed position in opposition to said holding means, said first switch portion tripping said latch means to release said switch' lever means from its closed position when said first switch portion is moved into said second range.

7. An electrical thermostat as set forth in claim 6 wherein said safety lever means comprises a movable rigid member carried by said housing means and operably associated with said reset means to be moved against said switch lever means to hold the same in its circuit open position when said reset means is moved to its actuated condition.

8. An electrical thermostat as set forth in claim 7 wherein said holding means comprises spring means carried by said housing means and normally tending to bias said switch lever means to its circuit open position.

9. An electrical thermostat as set forth in claim 8 wherein said reset means moves part of said switch lever means to be relatched by said latch means when said reset means is moved to its actuated condition.

10. An electrical thermostat as set forth in claim 9 wherein said switch lever means is flexible so that said rigid member can still hold said switch lever means in its circuit open position when said reset means is moved to its actuated condition to relatch said part of said switch lever means with said latch means.

References Cited UNITED STATES PATENTS 2,484,932 10/1949 Cox 200l16.l0 3,258,563 6/1966 Landau 337-66 BERNARD A. GILHEANY, Primary Examiner US. Cl. X.R. 337-66 

